She had a temporally complex relationship with the Doctor. She met the Doctor in an order different than he met her, as Charley Pollard and River Song later would. Eventually, however, their timelines synchronised, and she had a more-or-less linear relationship to the Doctor, starting in the later period of his sixth incarnation. Her temporal relationship to the Seventh Doctor was considerably more straightforward and linear.

She and her parents once walked through deep snow to their village hall whilst carrying all the props and costumes for a show for pensioners. This seemed to have created her insistence on never giving up. (AUDIO: The One Doctor)

Melanie had a keen interest in science from a very young age. Her uncle, Dr John Hallam — likely her mother's brother — was deeply influential to this childhood obsession, and she credited him with her later academic success at a London university. In 2003, Hallam told his colleague, Professor David Munro, that Mel was "very gifted" with computers. (AUDIO: Catch-1782) As a consequence of her education, she was adept in the human computer languages of BASIC, COBOL and FORTRAN. (AUDIO: The Juggernauts)

Mel first met the Sixth Doctor in Brighton in 1989 when she was twenty-five. However, as a consequence of the Doctor's trial prosecuted by the Valeyard, he already knew her. To him their first meeting was when she was pulled from her timestream by the Master and made to testify on the Doctor's behalf. For an indeterminate time — from the moment she met him in Brighton until the younger Sixth Doctor returned her to the side of an older Sixth Doctor on the planetOxyveguramosa — he had to pretend that he had originally met her in Brighton, as well. (PROSE: Business Unusual, PROSE: Time of Your Life) At the time, the younger Doctor considered her to be invisible and ineffectual. (AUDIO: The Wrong Doctors)

It was only after she was returned to his future self that their timelines synchronised, and he could speak with her in a more open way.

Mel and the Sixth Doctor's timelines were not asynchronous merely due to the unusual way in which they met. Even after their respective timelines seemed to come into harmony, Mel was often parted from the Sixth Doctor. At least twice, she was stranded for months away from him, even though very little time passed for him. When carried back in time to 1781 by a freak accident, the Doctor was unable to retrieve her until six months later in 1782. (AUDIO: Catch-1782) Later, she was accidentally left on Lethe and the Doctor was delayed for an additional three months. (AUDIO: The Juggernauts) On both occasions she became fully a resident of the era in which she found herself while waiting for the Doctor's uncertain return.

Her timeline with respect to the Seventh Doctor was, by contrast, far more orderly — though they, too, were heavily involved in a variety of time anomalies.

At some point during her travels with the Seventh Doctor, they visited the planet Nocturne. (AUDIO: Nocturne)

Her chronological placement with respect to other companions was tricky too. Technically, she both pre-dated and post-dated Evelyn Smythe. Smythe – or as she was then, Rossiter — once called Mel "my replacement". (AUDIO: Thicker than Water) Though they disagreed on many aspects of Bush and Evelyn's first meeting, another account agreed the bulk of Mel's travels with the Doctor was after Evelyn's. (PROSE: Instruments of Darkness) This view of events was likely one Mel held only at the moment of the encounter. The Mel from the trial had not yet been taken out of her timestream by the Time Lords; the Mel who met Evelyn would not yet have had knowledge she had met the Doctor long before their "first" encounter in Brighton. From the Doctor's viewpoint, he met Mel at the trial, took her back to her proper time, met Evelyn and travelled with her for several years before encountering Charley Pollard and a fictional version of Jamie McCrimmon and Zoe Heriot in the Land of Fiction, reunited with Mel in Brighton, reunited with Evelyn on Világ and then regenerated and continued travelling with Mel in his seventh incarnation.

Mel chose to leave the Doctor at a place and time radically different from her origin, without being enticed by a romantic relationship. Unlike most companions, she left the Doctor, but remained an adventurer. Trading one travelling companion for another, she departed the Doctor's side on Iceworld, only to begin her travels with the galactic confidence trickster Sabalom Glitz. (TV: Dragonfire)

Mel travelled with Glitz for about six months before deciding to try to go home. On her way she detoured to the planetAvalone, where she worked at a holiday camp owned by Avalonian Resorts, Inc.. Her progress towards Earth stalled and she succumbed to life on Avalone. After two years she chanced another run at Earth. She hacked into computer systems to send a message to Glitz to pick her up. Instead, she was "rescued" by Dr. Who and Jason, who imprisoned her in the Galactic Prison in the Land of Fiction. There, she met another prisoner, the Seventh Doctor. He, however, was a changed and considerably darker man than she had known. He revealed to her that he had manipulated her into leaving him on Iceworld because he knew what was coming (as Time's Champion) and couldn't have her as a companion. Incensed, she avoided his company and refused to travel with him in the TARDIS ever again. Ace, who was also much changed from the person that she had left behind on Iceworld, tried to calm her and explain the reasons why she and the Doctor were so much "harder" than the people she had known. Although the explanation did little to dispel her disillusionment, Mel accepted a ride from Ace. Mel thus returned to Pease Pottage in the 1990s thanks to Ace's time hopper. (PROSE: Head Games)

Mel had a cheery personality. She greeted most situations with a warm smile and good humour. She was an optimist who generally believed the best of people's natures, although she tempered this optimism with a realism and scepticism borne of her scientific education. Her generally perky personality could cool quite quickly if she detected a threat to herself, the Doctor or any friend. (TV: Terror of the Vervoids, AUDIO: The Fires of Vulcan, The Wishing Beast, The Juggernauts) Though she usually went by the informal "Mel", she sometimes insisted on being introduced as "Melanie" to those whom she didn't quite trust. (AUDIO: The Fires of Vulcan)

On still other occasions she allowed her logic to guide her swift and efficient action, as when she almost single-handedly defeated Davros and then derided the Doctor for not having killed the Daleks and him when given the chance. (AUDIO: The Juggernauts) She displayed extraordinary calm when she had to navigate Pompeii on foot during the eruption of Vesuvius in search of the Doctor's TARDIS — when he believed it lost and his life near its end. She could also fight against more internal threats, as when she fought off the effects of having been slowly drugged for six months with laudanum. (AUDIO: The Fires of Vulcan, Catch-1782)

Despite the occasional scream, Mel rarely expressed genuine, lasting fear of anything. However, she did once admit to a fear of heights. (AUDIO: Red)

Mel was a health enthusiast and a vegetarian, often encouraging the slightly portly Sixth Doctor to exercise more. (TV: Terror of the Vervoids) Though she remained staunchly vegetarian throughout her travels with the Doctor, (AUDIO: The Fires of Vulcan) her attempts to be the Doctor's de facto nutritionist almost vanished after that incarnation regenerated.

Her enthusiasm for healthy living, born of the hard-nosed logic of basic science, manifested itself in other ways. She was flatly dismissive of the supernatural — like ghosts — as scientifically ludicrous. (AUDIO: Catch-1782, Unregenerate!) Neither did she believe in fate. (AUDIO: The Juggernauts)

In her dealings with both of "her" Doctors, Mel was warmly affectionate. She sometimes found herself separated from him for months on end and always extremely glad to see him return. (AUDIO: The Juggernauts, Catch-1782) She was an especially enthusiastic travelling companion. Once, when asked what she would wish for, if she had the opportunity, she replied:

I was going to wish that things could go on just as they are — for as long as we could manage. I love all this, our lives, racketing about the galaxy.Mel [src]

The Doctor fails to enjoy his Mel-imposed diet of carrot juice and exercise

However, her proactive lifestyle led her to be bossy to both her Doctors. Not only did she try to reform the Sixth Doctor's health standards, she also demanded and apparently got him to abandon his motley outfit for a time. (AUDIO: Catch-1782) Likewise, she often spurred the Doctor to adventure, as when she insisted they stay on the Hyperion III to explore, against his better judgment (TV: Terror of the Vervoids), or when she insisted on staying in Pompeii knowing Vesuvius was about to erupt. Her at times boundless optimism could prove the buoy the Doctor needed to survive, as when she insisted that there must be a solution to a temporal paradox that the Doctor believed doomed them to death under the volcanic ash of Vesuvius. (AUDIO: The Fires of Vulcan)

Perhaps because of her highly adventurous nature, she sometimes found it difficult to cope with the mundane. She displayed reluctance at the sight of the rather ordinary Shangri-La holiday camp in Wales in 1959. (TV: Delta and the Bannermen) In his investigation of reports of a series of agent provocateurs known as "the Doctor" who had been involved in numerous unusual incidents, the journalist James Stevens found evidence of the Doctor and Mel's presence in Shangri-La during this incident. (PROSE: Who Killed Kennedy)

Mel's last name is never spoken in any televised appearance and the closing credits identify her only by her first name. Her surname is, however, regularly used in Big Finish Productions' audios and stories in other media.

According to his book The Companions, John Nathan-Turner planned to begin Season 24 with a storyline explaining how the Sixth Doctor met Mel. This story was never produced due to Colin Baker's removal from the role.

The Sixth Doctor's companions from stage plays are difficult to assert with certainty, as different actors played the Doctor in the same play. If a medium is not mentioned, then this incarnation did not have companions who were original to that medium; it does not mean that this Doctor failed to appear in that medium.